Inflexible
WordNet
adjective
(1) Resistant to being bent
"An inflexible iron bar"
"An inflexible knife blade";
(2) Incapable of change
"A man of inflexible purpose"
(3) Not making concessions
"Took an uncompromising stance in the peace talks"
"Uncompromising honesty"
(4) Incapable of adapting or changing to meet circumstances
"A rigid disciplinarian"
"An inflexible law"
"An unbending will to dominate"